// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

//! Network event types. These are are not the part of the protocol, but rather
//! events that happen on the network like DHT get/put results received.

use crate::{types::ProtocolName, NotificationsSink};

use bytes::Bytes;
use futures::channel::oneshot;
use libp2p::{kad::record::Key, PeerId};

use sc_network_common::{role::ObservedRole, sync::message::BlockAnnouncesHandshake};
use sp_runtime::traits::Block as BlockT;

/// Events generated by DHT as a response to get_value and put_value requests.
#[derive(Debug, Clone)]
#[must_use]
pub enum DhtEvent {
	/// The value was found.
	ValueFound(Vec<(Key, Vec<u8>)>),

	/// The requested record has not been found in the DHT.
	ValueNotFound(Key),

	/// The record has been successfully inserted into the DHT.
	ValuePut(Key),

	/// An error has occurred while putting a record into the DHT.
	ValuePutFailed(Key),
}

/// Type for events generated by networking layer.
#[derive(Debug, Clone)]
#[must_use]
pub enum Event {
	/// Event generated by a DHT.
	Dht(DhtEvent),

	/// Opened a substream with the given node with the given notifications protocol.
	///
	/// The protocol is always one of the notification protocols that have been registered.
	NotificationStreamOpened {
		/// Node we opened the substream with.
		remote: PeerId,
		/// The concerned protocol. Each protocol uses a different substream.
		/// This is always equal to the value of
		/// `sc_network::config::NonDefaultSetConfig::notifications_protocol` of one of the
		/// configured sets.
		protocol: ProtocolName,
		/// If the negotiation didn't use the main name of the protocol (the one in
		/// `notifications_protocol`), then this field contains which name has actually been
		/// used.
		/// Always contains a value equal to the value in
		/// `sc_network::config::NonDefaultSetConfig::fallback_names`.
		negotiated_fallback: Option<ProtocolName>,
		/// Role of the remote.
		role: ObservedRole,
		/// Received handshake.
		received_handshake: Vec<u8>,
	},

	/// Closed a substream with the given node. Always matches a corresponding previous
	/// `NotificationStreamOpened` message.
	NotificationStreamClosed {
		/// Node we closed the substream with.
		remote: PeerId,
		/// The concerned protocol. Each protocol uses a different substream.
		protocol: ProtocolName,
	},

	/// Received one or more messages from the given node using the given protocol.
	NotificationsReceived {
		/// Node we received the message from.
		remote: PeerId,
		/// Concerned protocol and associated message.
		messages: Vec<(ProtocolName, Bytes)>,
	},
}

/// Event sent to `SyncingEngine`
// TODO: remove once `NotificationService` is implemented.
pub enum SyncEvent<B: BlockT> {
	/// Opened a substream with the given node with the given notifications protocol.
	///
	/// The protocol is always one of the notification protocols that have been registered.
	NotificationStreamOpened {
		/// Node we opened the substream with.
		remote: PeerId,
		/// Received handshake.
		received_handshake: BlockAnnouncesHandshake<B>,
		/// Notification sink.
		sink: NotificationsSink,
		/// Channel for reporting accept/reject of the substream.
		tx: oneshot::Sender<bool>,
	},

	/// Closed a substream with the given node. Always matches a corresponding previous
	/// `NotificationStreamOpened` message.
	NotificationStreamClosed {
		/// Node we closed the substream with.
		remote: PeerId,
	},

	/// Notification sink was replaced.
	NotificationSinkReplaced {
		/// Node we closed the substream with.
		remote: PeerId,
		/// Notification sink.
		sink: NotificationsSink,
	},

	/// Received one or more messages from the given node using the given protocol.
	NotificationsReceived {
		/// Node we received the message from.
		remote: PeerId,
		/// Concerned protocol and associated message.
		messages: Vec<Bytes>,
	},
}
